The 39-year-old looked emotional after reaching the milestone in the 34th minute of the clash in Lisbon, converting Nuno Mendes' cross.

The strike, Ronaldo's first since June, extended his record haul of international goals to 131.

That put Portugal two up following Diogo Dalot's opener, but the Manchester United defender scored an own goal before half-time to make it a nervy second half.

History was made in San Marino, with the tiny country claiming their first ever competitive victory.

San Marino's only previous win was a friendly victory over Liechtenstein 20 years ago, and they defeated the same opposition 1-0 thanks to Nicko Sensoli's 53rd-minute winner, sparking wild celebrations.

European champions Spain were held to a goalless draw by Serbia in Belgrade, while Switzerland had Nico Elvedi and Granit Xhaka sent off in their 2-0 defeat by Denmark.

Patrick Dorgu scored the opening goal in the 82nd minute, with Pierre-Emile Hojbjerg adding the second following Xhaka's dismissal for a second yellow card.

Elsewhere, Newcastle striker Alexander Isak scored twice in Sweden's 3-1 victory over Azerbaijan, Slovakia defeated Estonia 1-0 and 10-man Bulgaria drew 0-0 with Belarus.

All the UEFA Nations League results:

(05/09/2024)

Group A1: Portugal 2-1 Croatia, Scotland 2-3 Poland

Group A4: Denmark 2-0 Switzerland, Serbia 0-0 Spain

Group C1: Azerbaijan 1-3 Sweden, Estonia 0-1 Slovakia

Group C3: Belarus 0-0 Bulgaria, Northern Ireland 2-0 Luxembourg

Group D1: San Marino 1-0 Liechtenstein

Nations League roundup: Cristiano Ronaldo hits 900th goal in Portugal win